diff --git a/README.md b/README.md
index 92981ff1..9bdd7f76 100644
--- a/README.md
+++ b/README.md
@@ -38,6 +38,7 @@ The main features of GQL are:
 * Possibility to [validate the queries locally](https://gql.readthedocs.io/en/latest/usage/validation.html) using a GraphQL schema provided locally or fetched from the backend using an instrospection query
 * Supports GraphQL queries, mutations and subscriptions
 * Supports [sync or async usage](https://gql.readthedocs.io/en/latest/async/index.html), [allowing concurrent requests](https://gql.readthedocs.io/en/latest/advanced/async_advanced_usage.html#async-advanced-usage)
+* Supports [File uploads](https://gql.readthedocs.io/en/latest/usage/file_upload.html)
 
 ## Installation
 
diff --git a/docs/transports/aiohttp.rst b/docs/transports/aiohttp.rst
index cdca6f45..a54809cc 100644
--- a/docs/transports/aiohttp.rst
+++ b/docs/transports/aiohttp.rst
@@ -1,3 +1,5 @@
+.. _aiohttp_transport:
+
 AIOHTTPTransport
 ================
 
diff --git a/docs/usage/file_upload.rst b/docs/usage/file_upload.rst
new file mode 100644
index 00000000..d900df95
--- /dev/null
+++ b/docs/usage/file_upload.rst
@@ -0,0 +1,69 @@
+File uploads
+============
+
+GQL supports file uploads with the :ref:`aiohttp transport <aiohttp_transport>`
+using the `GraphQL multipart request spec`_.
+
+.. _GraphQL multipart request spec: https://github.com/jaydenseric/graphql-multipart-request-spec
+
+Single File
+-----------
+
+In order to upload a single file, you need to:
+
+* set the file as a variable value in the mutation
+* provide the opened file to the `variable_values` argument of `execute`
+* set the `upload_files` argument to True
+
+.. code-block:: python
+
+    transport = AIOHTTPTransport(url='YOUR_URL')
+
+    client = Client(transport=sample_transport)
+
+    query = gql('''
+      mutation($file: Upload!) {
+        singleUpload(file: $file) {
+          id
+        }
+      }
+    ''')
+
+    with open("YOUR_FILE_PATH", "rb") as f:
+
+        params = {"file": f}
+
+        result = client.execute(
+            query, variable_values=params, upload_files=True
+        )
+
+File list
+---------
+
+It is also possible to upload multiple files using a list.
+
+.. code-block:: python
+
+    transport = AIOHTTPTransport(url='YOUR_URL')
+
+    client = Client(transport=sample_transport)
+
+    query = gql('''
+      mutation($files: [Upload!]!) {
+        multipleUpload(files: $files) {
+          id
+        }
+      }
+    ''')
+
+    f1 = open("YOUR_FILE_PATH_1", "rb")
+    f2 = open("YOUR_FILE_PATH_1", "rb")
+
+    params = {"files": [f1, f2]}
+
+    result = client.execute(
+        query, variable_values=params, upload_files=True
+    )
+
+    f1.close()
+    f2.close()
diff --git a/docs/usage/index.rst b/docs/usage/index.rst
index 2d5d5fd3..a7dd4d56 100644
--- a/docs/usage/index.rst
+++ b/docs/usage/index.rst
@@ -9,3 +9,4 @@ Usage
    subscriptions
    variables
    headers
+   file_upload
diff --git a/gql/transport/aiohttp.py b/gql/transport/aiohttp.py
index 2ae83999..f17d3f5b 100644
--- a/gql/transport/aiohttp.py
+++ b/gql/transport/aiohttp.py
@@ -1,3 +1,5 @@
+import json
+import logging
 from ssl import SSLContext
 from typing import Any, AsyncGenerator, Dict, Optional, Union
 
@@ -8,6 +10,7 @@
 from aiohttp.typedefs import LooseCookies, LooseHeaders
 from graphql import DocumentNode, ExecutionResult, print_ast
 
+from ..utils import extract_files
 from .async_transport import AsyncTransport
 from .exceptions import (
     TransportAlreadyConnected,
@@ -16,6 +19,8 @@
     TransportServerError,
 )
 
+log = logging.getLogger(__name__)
+
 
 class AIOHTTPTransport(AsyncTransport):
     """:ref:`Async Transport <async_transports>` to execute GraphQL queries
@@ -32,7 +37,7 @@ def __init__(
         auth: Optional[BasicAuth] = None,
         ssl: Union[SSLContext, bool, Fingerprint] = False,
         timeout: Optional[int] = None,
-        client_session_args: Dict[str, Any] = {},
+        client_session_args: Optional[Dict[str, Any]] = None,
     ) -> None:
         """Initialize the transport with the given aiohttp parameters.
 
@@ -54,7 +59,6 @@ def __init__(
         self.ssl: Union[SSLContext, bool, Fingerprint] = ssl
         self.timeout: Optional[int] = timeout
         self.client_session_args = client_session_args
-
         self.session: Optional[aiohttp.ClientSession] = None
 
     async def connect(self) -> None:
@@ -81,7 +85,8 @@ async def connect(self) -> None:
                 )
 
             # Adding custom parameters passed from init
-            client_session_args.update(self.client_session_args)
+            if self.client_session_args:
+                client_session_args.update(self.client_session_args)  # type: ignore
 
             self.session = aiohttp.ClientSession(**client_session_args)
 
@@ -104,7 +109,8 @@ async def execute(
         document: DocumentNode,
         variable_values: Optional[Dict[str, str]] = None,
         operation_name: Optional[str] = None,
-        extra_args: Dict[str, Any] = {},
+        extra_args: Dict[str, Any] = None,
+        upload_files: bool = False,
     ) -> ExecutionResult:
         """Execute the provided document AST against the configured remote server
         using the current session.
@@ -118,25 +124,70 @@ async def execute(
         :param variables_values: An optional Dict of variable values
         :param operation_name: An optional Operation name for the request
         :param extra_args: additional arguments to send to the aiohttp post method
+        :param upload_files: Set to True if you want to put files in the variable values
         :returns: an ExecutionResult object.
         """
 
         query_str = print_ast(document)
+
         payload: Dict[str, Any] = {
             "query": query_str,
         }
 
-        if variable_values:
-            payload["variables"] = variable_values
         if operation_name:
             payload["operationName"] = operation_name
 
-        post_args = {
-            "json": payload,
-        }
+        if upload_files:
+
+            # If the upload_files flag is set, then we need variable_values
+            assert variable_values is not None
+
+            # If we upload files, we will extract the files present in the
+            # variable_values dict and replace them by null values
+            nulled_variable_values, files = extract_files(variable_values)
+
+            # Save the nulled variable values in the payload
+            payload["variables"] = nulled_variable_values
+
+            # Prepare aiohttp to send multipart-encoded data
+            data = aiohttp.FormData()
+
+            # Generate the file map
+            # path is nested in a list because the spec allows multiple pointers
+            # to the same file. But we don't support that.
+            # Will generate something like {"0": ["variables.file"]}
+            file_map = {str(i): [path] for i, path in enumerate(files)}
+
+            # Enumerate the file streams
+            # Will generate something like {'0': <_io.BufferedReader ...>}
+            file_streams = {str(i): files[path] for i, path in enumerate(files)}
+
+            # Add the payload to the operations field
+            operations_str = json.dumps(payload)
+            log.debug("operations %s", operations_str)
+            data.add_field(
+                "operations", operations_str, content_type="application/json"
+            )
+
+            # Add the file map field
+            file_map_str = json.dumps(file_map)
+            log.debug("file_map %s", file_map_str)
+            data.add_field("map", file_map_str, content_type="application/json")
+
+            # Add the extracted files as remaining fields
+            data.add_fields(*file_streams.items())
+
+            post_args: Dict[str, Any] = {"data": data}
+
+        else:
+            if variable_values:
+                payload["variables"] = variable_values
+
+            post_args = {"json": payload}
 
         # Pass post_args to aiohttp post method
-        post_args.update(extra_args)
+        if extra_args:
+            post_args.update(extra_args)
 
         if self.session is None:
             raise TransportClosed("Transport is not connected")
diff --git a/gql/utils.py b/gql/utils.py
index 8f47d97d..ce0318b0 100644
--- a/gql/utils.py
+++ b/gql/utils.py
@@ -1,5 +1,8 @@
 """Utilities to manipulate several python objects."""
 
+import io
+from typing import Any, Dict, Tuple
+
 
 # From this response in Stackoverflow
 # http://stackoverflow.com/a/19053800/1072990
@@ -8,3 +11,43 @@ def to_camel_case(snake_str):
     # We capitalize the first letter of each component except the first one
     # with the 'title' method and join them together.
     return components[0] + "".join(x.title() if x else "_" for x in components[1:])
+
+
+def is_file_like(value: Any) -> bool:
+    """Check if a value represents a file like object"""
+    return isinstance(value, io.IOBase)
+
+
+def extract_files(variables: Dict) -> Tuple[Dict, Dict]:
+    files = {}
+
+    def recurse_extract(path, obj):
+        """
+        recursively traverse obj, doing a deepcopy, but
+        replacing any file-like objects with nulls and
+        shunting the originals off to the side.
+        """
+        nonlocal files
+        if isinstance(obj, list):
+            nulled_obj = []
+            for key, value in enumerate(obj):
+                value = recurse_extract(f"{path}.{key}", value)
+                nulled_obj.append(value)
+            return nulled_obj
+        elif isinstance(obj, dict):
+            nulled_obj = {}
+            for key, value in obj.items():
+                value = recurse_extract(f"{path}.{key}", value)
+                nulled_obj[key] = value
+            return nulled_obj
+        elif is_file_like(obj):
+            # extract obj from its parent and put it into files instead.
+            files[path] = obj
+            return None
+        else:
+            # base case: pass through unchanged
+            return obj
+
+    nulled_variables = recurse_extract("variables", variables)
+
+    return nulled_variables, files
diff --git a/tests/conftest.py b/tests/conftest.py
index c2edc236..c2a15605 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -4,8 +4,10 @@
 import os
 import pathlib
 import ssl
+import tempfile
 import types
 from concurrent.futures import ThreadPoolExecutor
+from typing import Union
 
 import pytest
 import websockets
@@ -187,6 +189,35 @@ async def send_connection_ack(ws):
         await ws.send('{"event":"phx_reply", "payload": {"status": "ok"}, "ref": 1}')
 
 
+class TemporaryFile:
+    """Class used to generate temporary files for the tests"""
+
+    def __init__(self, content: Union[str, bytearray]):
+
+        mode = "w" if isinstance(content, str) else "wb"
+
+        # We need to set the newline to '' so that the line returns
+        # are not replaced by '\r\n' on windows
+        newline = "" if isinstance(content, str) else None
+
+        self.file = tempfile.NamedTemporaryFile(
+            mode=mode, newline=newline, delete=False
+        )
+
+        with self.file as f:
+            f.write(content)
+
+    @property
+    def filename(self):
+        return self.file.name
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, type, value, traceback):
+        os.unlink(self.filename)
+
+
 def get_server_handler(request):
     """Get the server handler.
 
diff --git a/tests/test_aiohttp.py b/tests/test_aiohttp.py
index 0e97655f..8f39319f 100644
--- a/tests/test_aiohttp.py
+++ b/tests/test_aiohttp.py
@@ -11,6 +11,8 @@
     TransportServerError,
 )
 
+from .conftest import TemporaryFile
+
 query1_str = """
     query getContinents {
       continents {
@@ -321,3 +323,360 @@ def test_code():
                 pass
 
     await run_sync_test(event_loop, server, test_code)
+
+
+file_upload_server_answer = '{"data":{"success":true}}'
+
+file_upload_mutation_1 = """
+    mutation($file: Upload!) {
+      uploadFile(input:{other_var:$other_var, file:$file}) {
+        success
+      }
+    }
+"""
+
+file_upload_mutation_1_operations = (
+    '{"query": "mutation ($file: Upload!) {\\n  uploadFile(input: {other_var: '
+    '$other_var, file: $file}) {\\n    success\\n  }\\n}\\n", "variables": '
+    '{"file": null, "other_var": 42}}'
+)
+
+file_upload_mutation_1_map = '{"0": ["variables.file"]}'
+
+file_1_content = """
+This is a test file
+This file will be sent in the GraphQL mutation
+"""
+
+
+async def single_upload_handler(request):
+
+    reader = await request.multipart()
+
+    field_0 = await reader.next()
+    assert field_0.name == "operations"
+    field_0_text = await field_0.text()
+    assert field_0_text == file_upload_mutation_1_operations
+
+    field_1 = await reader.next()
+    assert field_1.name == "map"
+    field_1_text = await field_1.text()
+    assert field_1_text == file_upload_mutation_1_map
+
+    field_2 = await reader.next()
+    assert field_2.name == "0"
+    field_2_text = await field_2.text()
+    assert field_2_text == file_1_content
+
+    field_3 = await reader.next()
+    assert field_3 is None
+
+    return web.Response(text=file_upload_server_answer, content_type="application/json")
+
+
+@pytest.mark.asyncio
+async def test_aiohttp_file_upload(event_loop, aiohttp_server):
+    app = web.Application()
+    app.router.add_route("POST", "/", single_upload_handler)
+    server = await aiohttp_server(app)
+
+    url = server.make_url("/")
+
+    sample_transport = AIOHTTPTransport(url=url, timeout=10)
+
+    with TemporaryFile(file_1_content) as test_file:
+
+        async with Client(transport=sample_transport,) as session:
+
+            query = gql(file_upload_mutation_1)
+
+            file_path = test_file.filename
+
+            with open(file_path, "rb") as f:
+
+                params = {"file": f, "other_var": 42}
+
+                # Execute query asynchronously
+                result = await session.execute(
+                    query, variable_values=params, upload_files=True
+                )
+
+            success = result["success"]
+
+            assert success
+
+
+@pytest.mark.asyncio
+async def test_aiohttp_file_upload_without_session(
+    event_loop, aiohttp_server, run_sync_test
+):
+
+    app = web.Application()
+    app.router.add_route("POST", "/", single_upload_handler)
+    server = await aiohttp_server(app)
+
+    url = server.make_url("/")
+
+    def test_code():
+        sample_transport = AIOHTTPTransport(url=url, timeout=10)
+
+        with TemporaryFile(file_1_content) as test_file:
+
+            client = Client(transport=sample_transport,)
+
+            query = gql(file_upload_mutation_1)
+
+            file_path = test_file.filename
+
+            with open(file_path, "rb") as f:
+
+                params = {"file": f, "other_var": 42}
+
+                result = client.execute(
+                    query, variable_values=params, upload_files=True
+                )
+
+                success = result["success"]
+
+                assert success
+
+    await run_sync_test(event_loop, server, test_code)
+
+
+# This is a sample binary file content containing all possible byte values
+binary_file_content = bytes(range(0, 256))
+
+
+async def binary_upload_handler(request):
+
+    reader = await request.multipart()
+
+    field_0 = await reader.next()
+    assert field_0.name == "operations"
+    field_0_text = await field_0.text()
+    assert field_0_text == file_upload_mutation_1_operations
+
+    field_1 = await reader.next()
+    assert field_1.name == "map"
+    field_1_text = await field_1.text()
+    assert field_1_text == file_upload_mutation_1_map
+
+    field_2 = await reader.next()
+    assert field_2.name == "0"
+    field_2_binary = await field_2.read()
+    assert field_2_binary == binary_file_content
+
+    field_3 = await reader.next()
+    assert field_3 is None
+
+    return web.Response(text=file_upload_server_answer, content_type="application/json")
+
+
+@pytest.mark.asyncio
+async def test_aiohttp_binary_file_upload(event_loop, aiohttp_server):
+    app = web.Application()
+    app.router.add_route("POST", "/", binary_upload_handler)
+    server = await aiohttp_server(app)
+
+    url = server.make_url("/")
+
+    sample_transport = AIOHTTPTransport(url=url, timeout=10)
+
+    with TemporaryFile(binary_file_content) as test_file:
+
+        async with Client(transport=sample_transport,) as session:
+
+            query = gql(file_upload_mutation_1)
+
+            file_path = test_file.filename
+
+            with open(file_path, "rb") as f:
+
+                params = {"file": f, "other_var": 42}
+
+                # Execute query asynchronously
+                result = await session.execute(
+                    query, variable_values=params, upload_files=True
+                )
+
+            success = result["success"]
+
+            assert success
+
+
+file_upload_mutation_2 = """
+    mutation($file1: Upload!, $file2: Upload!) {
+      uploadFile(input:{file1:$file, file2:$file}) {
+        success
+      }
+    }
+"""
+
+file_upload_mutation_2_operations = (
+    '{"query": "mutation ($file1: Upload!, $file2: Upload!) {\\n  '
+    'uploadFile(input: {file1: $file, file2: $file}) {\\n    success\\n  }\\n}\\n", '
+    '"variables": {"file1": null, "file2": null}}'
+)
+
+file_upload_mutation_2_map = '{"0": ["variables.file1"], "1": ["variables.file2"]}'
+
+file_2_content = """
+This is a second test file
+This file will also be sent in the GraphQL mutation
+"""
+
+
+@pytest.mark.asyncio
+async def test_aiohttp_file_upload_two_files(event_loop, aiohttp_server):
+    async def handler(request):
+
+        reader = await request.multipart()
+
+        field_0 = await reader.next()
+        assert field_0.name == "operations"
+        field_0_text = await field_0.text()
+        assert field_0_text == file_upload_mutation_2_operations
+
+        field_1 = await reader.next()
+        assert field_1.name == "map"
+        field_1_text = await field_1.text()
+        assert field_1_text == file_upload_mutation_2_map
+
+        field_2 = await reader.next()
+        assert field_2.name == "0"
+        field_2_text = await field_2.text()
+        assert field_2_text == file_1_content
+
+        field_3 = await reader.next()
+        assert field_3.name == "1"
+        field_3_text = await field_3.text()
+        assert field_3_text == file_2_content
+
+        field_4 = await reader.next()
+        assert field_4 is None
+
+        return web.Response(
+            text=file_upload_server_answer, content_type="application/json"
+        )
+
+    app = web.Application()
+    app.router.add_route("POST", "/", handler)
+    server = await aiohttp_server(app)
+
+    url = server.make_url("/")
+
+    sample_transport = AIOHTTPTransport(url=url, timeout=10)
+
+    with TemporaryFile(file_1_content) as test_file_1:
+        with TemporaryFile(file_2_content) as test_file_2:
+
+            async with Client(transport=sample_transport,) as session:
+
+                query = gql(file_upload_mutation_2)
+
+                file_path_1 = test_file_1.filename
+                file_path_2 = test_file_2.filename
+
+                f1 = open(file_path_1, "rb")
+                f2 = open(file_path_2, "rb")
+
+                params = {
+                    "file1": f1,
+                    "file2": f2,
+                }
+
+                result = await session.execute(
+                    query, variable_values=params, upload_files=True
+                )
+
+                f1.close()
+                f2.close()
+
+                success = result["success"]
+
+                assert success
+
+
+file_upload_mutation_3 = """
+    mutation($files: [Upload!]!) {
+      uploadFiles(input:{files:$files}) {
+        success
+      }
+    }
+"""
+
+file_upload_mutation_3_operations = (
+    '{"query": "mutation ($files: [Upload!]!) {\\n  uploadFiles(input: {files: $files})'
+    ' {\\n    success\\n  }\\n}\\n", "variables": {"files": [null, null]}}'
+)
+
+file_upload_mutation_3_map = '{"0": ["variables.files.0"], "1": ["variables.files.1"]}'
+
+
+@pytest.mark.asyncio
+async def test_aiohttp_file_upload_list_of_two_files(event_loop, aiohttp_server):
+    async def handler(request):
+
+        reader = await request.multipart()
+
+        field_0 = await reader.next()
+        assert field_0.name == "operations"
+        field_0_text = await field_0.text()
+        assert field_0_text == file_upload_mutation_3_operations
+
+        field_1 = await reader.next()
+        assert field_1.name == "map"
+        field_1_text = await field_1.text()
+        assert field_1_text == file_upload_mutation_3_map
+
+        field_2 = await reader.next()
+        assert field_2.name == "0"
+        field_2_text = await field_2.text()
+        assert field_2_text == file_1_content
+
+        field_3 = await reader.next()
+        assert field_3.name == "1"
+        field_3_text = await field_3.text()
+        assert field_3_text == file_2_content
+
+        field_4 = await reader.next()
+        assert field_4 is None
+
+        return web.Response(
+            text=file_upload_server_answer, content_type="application/json"
+        )
+
+    app = web.Application()
+    app.router.add_route("POST", "/", handler)
+    server = await aiohttp_server(app)
+
+    url = server.make_url("/")
+
+    sample_transport = AIOHTTPTransport(url=url, timeout=10)
+
+    with TemporaryFile(file_1_content) as test_file_1:
+        with TemporaryFile(file_2_content) as test_file_2:
+
+            async with Client(transport=sample_transport,) as session:
+
+                query = gql(file_upload_mutation_3)
+
+                file_path_1 = test_file_1.filename
+                file_path_2 = test_file_2.filename
+
+                f1 = open(file_path_1, "rb")
+                f2 = open(file_path_2, "rb")
+
+                params = {"files": [f1, f2]}
+
+                # Execute query asynchronously
+                result = await session.execute(
+                    query, variable_values=params, upload_files=True
+                )
+
+                f1.close()
+                f2.close()
+
+                success = result["success"]
+
+                assert success